Conventional swash plate compressors utilize a rotating swash plate, driven by a drive shaft, to drive a piston. The piston is used to transfer fluid from the low pressure side of an air conditioning system or other device to the high pressure side. Conventional swash plate compressors utilize an elbow to transfer the rotational drive of the drive shaft to the swash plate. The utilization of an elbow, or similar mechanism, to transfer the rotational drive of the drive shaft has several undesirable characteristics. This conventional design transfers undesirable stresses to the swash plate requiring the swash plate to be designed for a higher strength. This adds to the size, weight, and cost of the swash plate compressor. The presence alone of the elbow or similar mechanism adds to the size, weight, complexity and manufacturing cost of the conventional swash plate compressor. In addition, the elbow, as it rotates with the drive shaft, limits the potential travel distance of the piston.
It is known that varying the angle of the swash plate relative to the drive shaft allows the swash plate compressor to produce variable fluid transfer rates. One known design utilizes a biasing spring and the crankcase pressure within the compressor to vary the angle of the swash plate. This crankcase pressure can lead to undesirable stresses on the swash plate and can have a negative effect on the vibrational characteristics of the swash plate compressor.
Finally, the piston driving mechanisms in known variable swash plate compressors utilize multiple pivot locations. The swash plate itself typically slides and/or rotates axially on the drive shaft, the elbow joint slides and/or rotates about a pin in the elbow, and the piston joint rotates about its connection with the swash plate. The position and rotation of the swash plate, the elbow, and the piston in relation to each pivot location controls the path of the piston. These multiple pivot locations often result in a variable Top-Dead-Center ("TDC") of the piston. The TDC of the piston is the distance between the piston face and the piston chamber outlet face at the top of the piston cycle. Variations in the piston TDC result in undesirable variations in the variable swash plate compressor's output.
Therefore, there is a need for a variable swash plate compressor design that reduces the stresses in the swash plate, allows for greater piston travel without increasing the compressor size, reduces undesirable vibrational characteristics, reduces variation in piston TDC, and reduces the size, weight, and manufacturing cost of known variable swash plate compressor designs.